The decay B-0 --> J/psi K-S(0) is reconstructed with J/psi --> e(+)e(-) or
mu (+)mu (-) and K-S(0) --> pi (+)pi (-). From the full ALEPH dataset at LE
P1 of about 4 million hadronic Z decays, 23 candidates are selected with an
estimated purity of 71%, They are used to measure the CP asymmetry of this
decay, given by sin 2 beta in the Standard Model, with the result sin 2 be
ta = 0.84(-1.04)(+0.82) +/- 0.16. This is combined with existing measuremen
ts from other experiments, and increases the confidence level that CP viola
tion has been observed in this channel to 98%. (C) 2000 Elsevier Science B.
V. All rights reserved.